1. Field of the Invention
The present invention relates generally to the field of bicycles and more particularly to an improved bicycle pedal and crank assembly.
2. Background Art
A number of pedal and crank designs have been made commercially available. Pedal designs include basic pedals and a variety of clipless versions for clamping shoes to pedals. Something that all pedals have in common is that they employ a spindle that is fixedly mounted to the crank arm, a pedal body that rotates about the spindle, and bearings or bushings between the pedal body and the spindle. The pedal spindle is always rigidly connected to the crank arm, usually by threading the spindle directly into the crank arm. The pedal spindle never turns relative to the crank arm.
Cranks typically have a threaded hole at the end of each crank arm for attaching the pedal spindle. Most cranks connect to a bottom bracket axle on the end of each arm opposite the pedal. The bottom bracket connects to the bottom bracket housing of the bicycle frame, and normally includes two or more bearings for the bottom bracket axle to turn. That way, the crank arms rotate smoothly relative to the bicycle frame. Some cranks have integrated the bottom bracket so that the bottom bracket axle is permanently connected to at least one of the crank arms. In some designs, this allows the bottom bracket axle to be made larger and the bearings to be moved outboard, stiffening the system, and/or reducing the system weight. In no cases is there a bearing incorporated into the pedal end of crank arms.
In bicycling, weight is extremely important because the power that a human produces is relatively small. Even small savings in weight can be extremely beneficial to racers and people who cycle long distances.
Pedals typically contain from 10 to 50 components. For example, a typical double side entry prior art clipless pedal, U.S. Pat. No. 5,203,229, has 39 components not including the cleat. Generally, clipless pedals contain more components than basic pedals because the mechanism for clamping onto a cleat usually adds parts. Generally, more components leads to higher costs and poorer performance in adverse environmental conditions.
Pedals are often used in extreme conditions. This is especially true because pedals are low to the ground and interface with the rider's shoe. Pedals are exposed to dirt, rain, mud, snow, and varying temperatures. Because of these factors, sealing the bearings and bushings from contamination is extremely important. Currently, because the seals are located on the pedal, they are in direct contact with the rider's shoes, which are often contaminated with dirt, mud, sand, etc.
For many pedals on the market, rebuilding the bearings and bushings is difficult or impossible for most consumers. Oftentimes, it is very difficult to access the bearings or bushing, and once accessed, it is often difficult to remove them. For pedals that use loose ball bearings rather than cartridge bearings or bushings, it is easy to lose the balls during disassembly, and nearly impossible to reassemble the balls and properly adjust the bearings. Most pedals that use loose ball bearings are realistically disposable rather than rebuildable.
Stack height is the distance between the bottom of the rider's shoe and the centerline of the spindles of their pedals. In order to lower the rider's center of gravity for better stability, it is preferable to have the lowest stack height possible. Currently, all pedals have at minimum a spindle, some form of bearings, and a body. The stack height is determined by adding these layers. U.S. Pat. No. 4,080,017 discloses one way to reduce stack height in a bicycle pedal, but at the expense of increasing Q-factor.
Q-factor is the distance between the center of the pedal body to the centerline of the bicycle. Essentially, Q-factor is a measure of how far the rider's feet are apart from each other. Q-factor is determined by a combination of the bottom bracket spindle length, the crank offset, and length of the pedal. Many bicyclists have a strong preference for the Q-factor depending on their leg length and their particular physiology. Most commonly, bicyclists can suffer from knee pain and damage if the Q-factor is too large.